This paper presents the designs of two observers, which are: the extended Kalman filterand the nonlinear passive observer. Based on the measured values of ship position andheading, the observers estimate the surge, sway and yaw velocities of the ship motion.The observers make use of the simplified nonlinear mathematical model of ship motion inwhich the neglected ship dynamics and disturbances are modelled using bias. The designedobservers firstly have been simulated on a computer model where their parameters werecalibrated, and then were implemented on the physical model of the training ship “BlueLady” in the ship handling centre in Ilawa-Kamionka. The comparative analysis wasdone with respect to the estimated variables describing the ship motion in three directions: surge, swayand yaw
